4101:3-11-01
Storm drainage.

[Comment: When a reference is
made within this rule to a federal statutory provision, an industry consensus
standard, or any other technical publication, the specific date and title of
the publication as well as the name and address of the promulgating agency are
listed in rule
4101:3-13-01 of the
Administrative Code. The application of the referenced standards shall be
limited and as prescribed in section 102.5 of rule
4101:1-1-01 of the
Administrative Code.]

SECTION 1101

GENERAL

1101.1 Scope. The provisions of this chapter shall govern the materials,
design, construction and installation of storm drainage.

1101.2 Where
required. All roofs, paved areas, yards,
courts and courtyards in buildings shall drain into a separate
storm sewer system, or a combined sewer system, or to an approved place of
disposal. For one-and two-, and three- family dwellings, and
where approved, storm water is permitted to discharge onto flat areas, such as
streets or lawns, provided that the storm water flows away from the
building.

1101.3 Prohibited
drainage. Storm water shall not be drained
into sewers intended for sewage only.

1101.4 Tests. The conductors and the building storm drain shall be
tested in accordance with Section 312.

1101.5 Change in size.
The size of a drainage pipe shall not be
reduced in the direction of flow.

1101.6 Fittings and
connections. All connections and changes
in direction of the storm drainage system shall be made with approved
drainage-type fittings in accordance with Table 706.3. The fittings shall not
obstruct or retard flow in the system.

1101.7 Roof design.
Roofs shall be designed for the maximum
possible depth of water that will pond thereon as determined by the relative
levels of roof deck and overflow weirs, scuppers, edges or serviceable drains
in combination with the deflected structural elements. In determining the
maximum possible depth of water, all primary roof drainage means shall be
assumed to be blocked.

1101.8 Cleanouts required.
Cleanouts shall be installed in the storm
drainage system and shall comply with the provisions of this code for sanitary
drainage pipe cleanouts.

1102.7 Fittings.
Pipe fittings shall be approved for
installation with the piping material installed, and shall conform to the
respective pipe standards or one of the standards listed in Table 1102.7. The
fittings shall not have ledges, shoulders or reductions capable of retarding or
obstructing flow in the piping. Threaded drainage pipe fittings shall be of the
recessed drainage type.

1103.1 Main trap. Leaders and storm drains connected to a combined sewer
shall be trapped. Individual storm water traps shall be installed on the storm
water drain branch serving each conductor, or a single trap shall be installed
in the main storm drain just before its connection with the combined building
sewer or the public sewer.

1103.2 Material.
Storm water traps shall be of the same
material as the piping system to which they are attached.

1103.3 Size. Traps for individual conductors shall be the same size as
the horizontal drain to which they are connected.

1103.4 Cleanout.
An accessible cleanout shall be installed
on the building side of the trap.

SECTION 1104

CONDUCTORS AND
CONNECTIONS

1104.1 Prohibited use.
Conductor pipes shall not be used as soil,
waste or vent pipes, and soil, waste or vent pipes shall not be used as
conductors.

1104.2 Combining storm with
sanitary drainage. The sanitary and storm
drainage systems of a structure shall be entirely separate except where
combined sewer systems are utilized. Where a combined sewer is utilized, the
building storm drain shall be connected to the sanitary sewer exterior
to the building.

1104.3 Floor drains.
Floor drains shall not be connected to a
storm drain.

SECTION 1105

ROOF DRAINS

1105.1 Strainers.
Roof drains shall have strainers extending
not less than 4 inches (102 mm) above the surface of the roof immediately
adjacent to the roof drain. Strainers shall have an available inlet area, above
roof level, of not less than one and one-half times the area of the conductor
or leader to which the drain is connected.

1105.2 Flat decks.
Roof drain strainers for use on sun decks,
parking decks and similar areas that are normally serviced and maintained shall
comply with Section 1105.1 or shall be of the flat-surface type, installed
level with the deck, with an available inlet area not less than two times the
area of the conductor or leader to which the drain is connected.

1105.3 Roof drain
flashings. The connection between roofs
and roof drains which pass through the roof and into the interior of the
building shall be made water-tight by the use of approved flashing
material.

SECTION 1106

SIZE OF CONDUCTORS, LEADERS AND
STORM DRAINS

1106.1 General. The size of the vertical conductors and leaders, building
storm drains, building storm sewers, and any horizontal branches of such drains
or sewers shall be based on the 100-year hourly rainfall rate indicated in
Figure 1106.1 or on other rainfall rates determined from approved local weather
data.

a.Sizes indicated are the diameter of
circular piping. This table is applicable to piping of other shapes, provided
the cross-sectional shape fully encloses a circle of the diameter indicated in
this table. For rectangular leaders, see Table 1106.2(2).Interpolation is
permitted for pipe sizes that fall between those listed in this table.

b. For shapes not included in this
table, Equation 11-1 shall be used to determine the equivalent circular
diameter, De, of rectangular piping for use in
interpolation using the data from Table 1106.2(1).

De, = [width *
length] 1/2 (Equation 11-1)

where:

De = equivalent
circular diameter and De, width and length are in
inches.

1106.2 Vertical conductors and
leaders. Vertical conductors and leaders
shall be sized for the maximum projected roof area, in accordance with Tables
1106.2(1) and 1106.2(2).

1106.3 Building storm drains and
sewers. The size of the building storm
drain, building storm sewer and their horizontal branches having a slope of
one-half unit or less vertical in 12 units horizontal (4-percent slope) shall
be based on the maximum projected roof area in accordance with Table 1106.3.
The minimum slope of horizontal branches shall be one-eighth unit vertical in
12 units horizontal (1-percent slope) unless otherwise approved.

1106.4 Vertical walls.
In sizing roof drains and storm drainage
piping, one-half of the area of any vertical wall that diverts rainwater to the
roof shall be added to the projected roof area for inclusion in calculating the
required size of vertical conductors, leaders and horizontal storm drainage
piping.

1106.6 Size of roof gutters.
The size of semicircular gutters shall be
based on the maximum projected roof area in accordance with Table 1106.6.

SECTION 1107

SECONDARY (EMERGENCY) ROOF
DRAINS

1107.1 Secondary drainage
required. Secondary (emergency) roof
drains or scuppers shall be provided where the roof perimeter construction
extends above the roof in such a manner that water will be entrapped if the
primary drains allow buildup for any reason.

1107.2 Separate systems required.
Secondary roof drain systems shall have
the end point of discharge separate from the primary system. Discharge shall be
above grade, in a location that would normally be observed by the building
occupants or maintenance personnel.

1107.3 Sizing of secondary
drains. Secondary (emergency) roof drain
systems shall be sized in accordance with Section 1106 based on the rainfall
rate for which the primary system is sized in Tables 1106.2, 1106.3 and 1106.6.
Scuppers shall be sized to prevent the depth of ponding water from exceeding
that for which the roof was designed as determined by Section 1101.7. Scuppers
shall not have an opening dimension of less than 4 inches (102 mm). The flow
through the primary system shall not be considered when sizing the secondary
roof drain system.

TABLE 1106.3

SIZE OF HORIZONTAL STORM
DRAINAGE PIPING

SIZE
OFHORIZONTALPIPING(inches)

HORIZONTALLY
PROJECTED ROOF AREA (square feet)

Rainfall rate
(inches per hour)

1

2

3

4

5

6

1/8 unit vertical in
12 units horizontal (1-percent slope)

3

3,288

1,644

1,096

822

657

548

4

7,520

3,760

2,506

1,800

1,504

1,253

5

13,360

6,680

4,453

3,340

2,672

2,227

6

21,400

10,700

7,133

5,350

4,280

3,566

8

46,000

23,000

15,330

11,500

9,200

7,600

10

82,800

41,400

27,600

20,700

16,580

13,800

12

133,200

66,600

44,400

33,300

26,650

22,200

15

218,000

109,000

72,800

59,500

47,600

39,650

1/4 unit vertical in
12 units horizontal (2-percent slope)

3

4,640

2,320

1,546

1,160

928

773

4

10,600

5,300

3,533

2,650

2,120

1,766

5

18,880

9,440

6,293

4,720

3,776

3,146

6

30,200

15,100

10,066

7,550

6,040

5,033

8

65,200

32,600

21,733

16,300

13,040

10,866

10

116,800

58,400

38,950

29,200

23,350

19,450

12

188,000

94,000

62,600

47,000

37,600

31,350

15

336,000

168,000

112,000

84,000

67,250

56,000

1/2 unit vertical in
12 units horizontal (4-percent slope)

3

6,576

3,288

2,295

1,644

1,310

1,096

4

15,040

7,520

5,010

3,760

3,010

2,500

5

26,720

13,360

8,900

6,680

5,320

4,450

6

42,800

21,400

13,700

10,700

8,580

7,140

8

92,000

46,000

30,650

23,000

18,400

15,320

10

171,600

85,800

55,200

41,400

33,150

27,600

12

266,400

133,200

88,800

66,600

53,200

44,400

15

476,000

238,000

158,800

119,000

95,300

79,250

SECTION 1108

COMBINED SANITARY AND STORM
SYSTEM

1108.1 Size of combined drains
and sewers. Deleted.

SECTION 1109

VALUES FOR CONTINUOUS
FLOW

1109.1 Equivalent roof area.
Where there is a continuous or
semicontinuous discharge into the building storm drain or building storm sewer,
such as from a pump, ejector, air conditioning plant or similar device, each
gallon per minute (L/m) of such discharge shall be computed as being equivalent
to 96 square feet (9 m2 ) of roof area, based on a
rainfall rate of 1 inch ( 25.4 mm) per hour

TABLE 1106.6

SIZE OF SEMICIRCULAR ROOF
GUTTERS

DIAMETEROF
GUTTERS(inches)

HORIZONTALLY
PROJECTED ROOF AREA (square feet)

Rainfall rate
(inches per hour)

1

2

3

4

5

6

1/16 unit vertical
in 12 units horizontal ( 0.5 -percent slope)

3

680

340

226

170

136

113

4

1,440

720

480

360

288

240

5

2,500

1,250

834

625

500

416

6

3,840

1,920

1,280

960

768

640

7

5,520

2,760

1,840

1,380

1,100

918

8

7,960

3,980

2,655

1,990

1,590

1,325

10

14,400

7,200

4,800

3,600

2,880

2,400

1/8 unit vertical 12
units horizontal (1-percent slope)

3

960

480

320

240

192

160

4

2,040

1,020

681

510

408

340

5

3,520

1,760

1,172

880

704

587

6

5,440

2,720

1,815

1,360

1,085

905

7

7,800

3,900

2,600

1,950

1,560

1,300

8

11,200

5,600

3,740

2,800

2,240

1,870

10

20,400

10,200

6,800

5,100

4,080

3,400

1/4 unit vertical in
12 units horizontal (2-percent slope)

3

1,360

680

454

340

272

226

4

2,880

1,440

960

720

576

480

5

5,000

2,500

1,668

1,250

1,000

834

7

11,040

5,520

3,860

2,760

2,205

1,840

8

15,920

7,960

5,310

3,980

3,180

2,655

10

28,800

14,400

9,600

7,200

5,750

4,800

1/2 unit vertical in
12 units horizontal (4-percent slope)

3

1,920

960

640

480

384

320

4

4,080

2,040

1,360

1,020

816

680

5

7,080

3,540

2,360

1,770

1,415

1,180

6

11,080

5,540

3,695

2,770

2,220

1,850

7

15,600

7,800

5,200

3,900

3,120

2,600

8

22,400

11,200

7,460

5,600

4,480

3,730

10

40,000

20,000

13,330

10,000

8,000

6,660

SECTION 1110

CONTROLLED FLOW ROOF DRAIN
SYSTEMS

1110.1 General. The roof of a structure shall be designed for the storage of
water where the storm drainage system is engineered for controlled flow. The
controlled flow roof drain system shall be an engineered system in accordance
with this section and the design, submittal, approval, inspection and testing
requirements of Sections 106.5, 107, and 108 of the building code and
Section 312 of this code. The controlled flow system shall be designed
based on the required rainfall rate in accordance with Section 1106.1.

1110.2 Control devices.
The control devices shall be installed so
that the rate of discharge of water per minute shall not exceed the values for
continuous flow as indicated in Section 1109.1.

1110.3 Installation.
Runoff control shall be by control
devices. Control devices shall be protected by strainers.

1110.4 Minimum number of roof
drains. Not less than two roof drains
shall be installed in roof areas 10,000 square feet (929 m
2) or less and not less than four 2 roof drains
shall be installed in roofs over 10,000 square feet (929 m
2 ) in area.

SECTION 1111

SUBSOIL DRAINS

1111.1 Subsoil drains.
Subsoil drains shall be open-jointed,
horizontally split or perforated pipe conforming to one of the standards listed
in Table 1102.5. Such drains shall not be less than 4 inches (102 mm) in
diameter. Where the building is subject to backwater, the subsoil drain shall
be protected by an accessibly located backwater valve. Subsoil drains shall
discharge to a trapped area drain, sump, dry well or approved location above
ground. The subsoil sump shall not be required to have either a gas-tight cover
or a vent. The sump and pumping system shall comply with Section 1113.1.

SECTION 1112

BUILDING SUBDRAINS

1112.1 Building subdrains.
Building subdrains located below the
public sewer level shall discharge into a sump or receiving tank, the contents
of which shall be automatically lifted and discharged into the drainage system
as required for building sumps. The sump and pumping equipment shall comply
with Section 1113.1.

1113.1.1 Pump capacity and head.
The sump pump shall be of a capacity and
head appropriate to anticipated use requirements.

1113.1.2 Sump pit.
The sump pit shall not be less than 18
inches (457 mm) in diameter and 24 inches (610 mm) deep, unless otherwise
approved. The pit shall be accessible and located such that all drainage flows
into the pit by gravity. The sump pit shall be constructed of tile, steel,
plastic, cast-iron, concrete or other approved material, with a removable cover
adequate to support anticipated loads in the area of use. The pit floor shall
be solid and provide permanent support for the pump.

1113.1.4 Piping.
Discharge piping shall meet the
requirements of Section 1102.2, 1102.3 or 1102.4 and shall include a
full open valve and a full flow check valve. Pipe and fittings
shall be the same size as, or larger than, pump discharge tapping.

Exception:
In buildings where the
"Residential Code of Ohio" applies, only a check valve shall be required,
located on the discharge piping from the pump or ejector.

1113.1.5 Water-powered
sump pumps. Water-powered
sump pumps are only to be used as a secondary back-up pump for the subsoil
drainage system and only with appropriate backflow protection in place as
required by Section 608.